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VOLUME 287 (2012) PAGES 5898–5909
This article has been withdrawn by the authors. The authors recently discovered that many of the results reported in this paper can be attributed to an artifact of gene transduction rather than the transduced gene itself, and therefore, the conclusions of this work are no longer valid. The withdrawal was initiated by the authors as soon as the new information became available.
A replication-deficient adenovirus (pLP-Adeno-X-PRLS, Clontech) was used to overexpress glypican-1 (GPC1), and empty adenovirus was used as control. Overexpression of GPC1 was confirmed by Western blotting. Recently, we performed transmission electron microscopy and detected adenoviral particles in Ad-GPC1 but not Ad-control infected cells. PCR analysis confirmed the presence of E1 protein in Ad-GPC1 but not in Ad-control. Therefore, we conclude that Ad-GPC1 has acquired the E1 gene from the HEK 293 packaging cells and has become replication competent. Considering the small scale of virus production used in these experiments, this is a very unlikely event, which appears to have occurred (Lochmüller, H., Jani, A., Huard, J., Prescott, S., Simoneau, M., Massie, B., Karpati, G., and Acsadi, G. (1994) Emergence of early region 1-containing replication-competent adenovirus in stocks of replication-defective adenovirus recombinants (ΔE1 + ΔE3) during multiple passages in 293 cells. Hum. Gene Ther. 5, 1485–1491 and Zhu, J., Grace, M., Casale, J., Chang, A. T., Musco, M. L., Bordens, R., Greenberg, R., Schaefer, E., Chang, A. T., Musco, M. L., and Indelicato, S. R. (1999) Characterization of replication-competent adenovirus isolates from large-scale production of a recombinant adenoviral vector. Hum. Gene Ther. 10, 113–121).
We prepared a new batch of Ad-GPC1 and repeated key experiments with U87 cells. Whereas GPC1 overexpression induced an increase in S-phase cells, we could not reproduce the dramatic effects on BrdU incorporation or on the cell cycle regulators, which we reported in this paper.
Also affected is the following publication, which is being retracted as well (Qiao, D., Meyer, K., and Friedl, A. (2013) Glypican-1 Stimulates S Phase Entry and DNA Replication in Human Glioma Cells and Normal Astrocytes. Mol. Cell Biol. 33, 4408–4421).